Physical channel design for network-assisted d2d

ABSTRACT

A method in a network node for multiplexing a physical channel between the network node and devices in a mixed wireless network, wherein the mixed wireless network comprises a cellular network comprising one or more cellular channels and a Device-to-Device (D2D) network comprising one or more D2D channels. The method includes time division multiplexing the physical channel between a first group of cellular channels and a first group of D2D channels, and frequency division multiplexing the physical channel between a second group of cellular channels and the first group of D2D channels.

TECHNICAL FIELD

Embodiments herein relate to a network node and a method therein. Inparticular, embodiments herein relate to multiplexing a physicalchannel.

BACKGROUND

Devices such as User Equipments (UE) are also known as e.g. mobileterminals, wireless terminals and/or mobile stations. Devices areenabled to communicate wirelessly in a wireless communications system orwireless communication system, sometimes also referred to as a cellularradio system or cellular networks. The communication may be performede.g. between two devices, between a device and a regular telephoneand/or between a device and a server via a Radio Access Network (RAN)and possibly one or more core networks, comprised within the wirelesscommunications system.

Devices may further be referred to as mobile telephones, cellulartelephones, or laptops with wireless capability, just to mention somefurther examples. The devices in the present context may be, forexample, portable, pocket-storable, hand-held, computer-comprised, orvehicle-mounted mobile devices, enabled to communicate voice and/ordata, via the RAN, with another entity, such as device or a server.

The wireless communications system covers a geographical area which isdivided into cell areas, wherein each cell area being served by a basestation, e.g. a Radio Base Station (RBS), which sometimes may bereferred to as e.g. “eNB”, “eNodeB”, “NodeB”, “B node”, or BTS (BaseTransceiver Station), depending on the technology and terminology used.The base stations may be of different classes such as e.g. macro eNodeB,home eNodeB or pico base station, based on transmission power andthereby also cell size. A cell is the geographical area where radiocoverage is provided by the base station at a base station site. Onebase station, situated on the base station site, may serve one orseveral cells. Further, each base station may support one or severalcommunication technologies. The base stations communicate over the airinterface operating on radio frequencies with the devices within rangeof the base stations.

In some RANs, several base stations may be connected, e.g. by landlinesor microwave, to a radio network controller, e.g. a Radio NetworkController (RNC) in Universal Mobile Telecommunications System (UMTS),and/or to each other. The radio network controller, also sometimestermed a Base Station Controller (BSC) e.g. in GSM, may supervise andcoordinate various activities of the plural base stations connectedthereto. GSM is an abbreviation for Global System for MobileCommunications (originally: Groupe Spécial Mobile).

In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE),base stations, which may be referred to as eNodeBs or even eNBs, may bedirectly connected to one or more core networks.

UMTS is a third generation mobile communication system, which evolvedfrom the GSM, and is intended to provide improved mobile communicationservices based on Wideband Code Division Multiple Access (WCDMA) accesstechnology. UMTS Terrestrial Radio Access Network (UTRAN) is essentiallya radio access network using wideband code division multiple access fordevices. The 3GPP has undertaken to evolve further the UTRAN and GSMbased radio access network technologies.

According to 3GPP GSM EDGE Radio Access Network (GERAN), a device has amulti-slot class, which determines the maximum transfer rate in theuplink and downlink direction. EDGE is an abbreviation for Enhanced Datarates for GSM Evolution. In the end of 2008 the first release, Release8, of the 3GPP Long Term Evolution (LTE) standard was finalized andlater releases have also been finalized.

Recent developments of the 3GPP LTE facilitate accessing local InternetProtocol (IP) based services in the home, office, public hot spot oreven outdoor environments. One of the important use cases for the localIP access and local connectivity involves the direct communicationbetween devices in close proximity, typically less than a few 10 s ofmeters, but sometimes up to a few hundred meters of each other.

In network-controlled so-called Device-to-Device (D2D) communications, anetwork such as a radio access network assists devices that are in theproximity of each other to discover one another, in a process referredto as device discovery, and establish a direct link referred to as D2Dbearer establishment, rather than a link via the base station. In fact,when two devices communicate with each other via a cellular basestation, the communication path involves an uplink hop and a downlinkhop, both with associated resources, as opposed to the single hop directD2D link. In the context of this disclosure, the expression Downlink(DL) is used for the transmission path from the base station to themobile station or device. The expression Uplink (UL) is used for thetransmission path in the opposite direction i.e. from the mobile stationor communication device to the base station.

The initiation of the establishment of the D2D link may be made by theradio access network or by any of the devices of the D2D pair. Innetwork initiated D2D link establishment, the network realizes that twocommunicating devices are in proximity of each other. In deviceinitiated D2D link establishment, the devices discover the proximity ofeach other and also some of their capabilities which is necessary forthem to establish a D2D link, similar to Bluetooth.

In network-controlled D2D communication, a network control functionperforms at least one of: a) provisioning of a discovery signal to beused between two devices to determine their proximity and/or D2D linkestimation, b) resource assignment for the D2D discovery signal and/or aD2D data channel and/or a D2D control channel, c) relaying ofinformation between the at least two devices, and d) configuration ofconnection parameters for the at least two devices of the D2D link, suchas power setting, e.g., actual, min, max, coding and modulation schemes,segmentation configuration, e.g., transport block sizes, parametersand/or security keys for encryption/integrity protection and protocolparameters.

A transmission in an LTE or Evolved Universal Terrestrial Radio AccessNetwork (E-UTRAN) is based on Orthogonal Frequency Division Multiplexing(OFDM), whose format may be modeled as an OFDM time-frequency grid. TheOFDM time-frequency grid is comprised in one axis of frequency valuesand in the other axis of time. The frequency axis is subdivided in anumber of frequency sub-carriers, with a spacing that may typicallycorrespond to 15 kHz, while the time axis is subdivided in OFDM symbolintervals.

Within the grid, a Physical Resource Block (PRB or RB) is a unit oftransmission resource consisting of twelve consecutive sub-carriers inthe frequency domain and one time slot, 0.5 ms, in the time domain.

The direct communication mode, or D2D communication, enables a number ofpotential gains over the traditional cellular technique, because D2Ddevices are much closer to one another than cellular devices that haveto communicate via a cellular access point, e.g., a base station:

-   -   Capacity gain: First, radio resources, e.g., OFDM RB, between        the D2D and cellular layers may be reused, i.e., reuse gain.        Second, a D2D link uses a single hop between the transmitter and        receiver points as opposed to the 2-hop link via a cellular        access point, i.e., hop gain.    -   Peak rate gain: due to the proximity and potentially favorable        propagation conditions, modulation and coding scheme (MCS) of        higher order may be applied, so that, the maximum achievable        data rate may be further improved, i.e., proximity gain;    -   Latency gain: When the devices communicate over a direct link,        the base station forwarding is short cut and the end-to-end        latency may decrease.

In a mixed cellular and D2D network resulting from the coexistence ofthese two systems, the Physical layer (PHY) channel design has to takeinto account the inter-system interference, i.e., interference betweencellular sub-system and D2D sub-system. The coexistence of the systemsmay result in two types of interference: 1) co-channel or co-RBinterference, i.e., interference on the same RB; and 2) inter-channel orinter-RB interference due to in-band emission, i.e., the interferencefrom allocated RB to un-allocated RBs within the band. Here a band maybe defined as a continuous frequency range (3GPP defined multiple bandsin 3GPP TS 36.101, EUTRA User Equipment (UE) radio transmission andreception, 2012.03), and a corresponding carrier frequency is a specificfrequency that is used to carry the radio signal which spans the wholefrequency band.

As shown by the following table defined by 3GPP (3GPP TS 36.101, EUTRAUser Equipment (UE) radio transmission and reception, 2012.03), thein-band emission, i.e., the interference from allocated RBs toun-allocated RBs within the band, is restricted to different levels fordifferent cases, depending on the specific value of the systembandwidth, allocated RB size, Error Vector Magnitude (EVM), transmissionpower, etc. First, for a general case, i.e., when the measurementbandwidth is 1 RB and the limit is expressed as a ratio of measuredpower in one non-allocated RB to the measured average power perallocated RB, where the averaging is done across all allocated RBs.Second, for an image frequencies case, i.e., when the applicablefrequencies for this limit are those that are enclosed in the reflectionof the allocated bandwidth, based on symmetry with respect to the centercarrier frequency, but excluding any allocated RBs. And third, for acarrier frequency leakage case, i.e., when the applicable frequenciesfor this limit are those that are enclosed in the RBs containing oradjacent to the DC frequency, but excluding any allocated RB.

TABLE 1 In-band Emission formula Parameter description Unit Limit(Note 1) Applicable Frequencies General dB max {−25 − 10 ·log₁₀(N_(RB)/L_(CRBs)), Any non-allocated (Note 2) 20 · log₁₀ EVM −3 − 5· (|Δ_(RB)|−1)/L_(CRBs), −57 dBm/180 kHz − P_(RB)} IQ Image dB −25 Imagefrequencies (Notes 2, 3) Carrier dBc −25 Output power >0 dBm Carrierfrequency (Notes 4, 5) leakage −20 −30 dBm ≦ Output power ≦0 dBm −10 −40dBm ≦ Output power <−30 dBm

Where N_(RB) is defined as the transmission bandwidth configuration,expressed in units of resource blocks, L_(CRBs) is defined as the lengthof a contiguous resource block allocation, |Δ_(RB)| is defined as thestarting frequency offset between the allocated RB and the measurednon-allocated RB, P_(RB) is defined as the transmitted power per 180 kHzin allocated RBs, measured in dBm. A simple calculation may be asfollows: For a general item, given a 5 MHz bandwidth, 5 RBs allocated toa cellular device, whose transmission signalling EVM=0.175, Tx power=23dBm, then the in-band emission would be I=max[−32, −18-x, −57], where xis the starting frequency offset between the allocated RB and themeasured non-allocated RB, e.g., x=0 for the first adjacent RB outsideof the allocated bandwidth, x=1 for the second, i.e., an emission from−18˜−32 dB would be caused. This emission would be more serious for moreallocated RB size, RBs most next to the allocated RB, larger EVM. Asshown in FIG. 1, even if a −30 dB emission is assumed, a nearby cellulardevice, e.g., 10 m, would cause failure of D2D communication onneighboring band. According to International MobileTelecommunications-Advanced (IMT-A) Indoor Non-Line of Sight (NLOS),path loss model: 43.3*log10(10 m)+11.5+20*log10(2 GHz)=60.82 dB.

Thus, co-channel and/or inter-channel interference is a problem in amixed wireless network.

SUMMARY

It is therefore an object of embodiments herein to provide a way ofimproving the performance in a mixed cellular/D2D wireless network.

According to a first aspect of embodiments herein, the object isachieved by a method in a network node for multiplexing a physicalchannel between the network node and devices. The network node and thedevices are comprised in a mixed wireless network. The mixed wirelessnetwork further comprises cellular network comprising one or morecellular channels and a Device-to-Device, D2D. network comprising one ormore D2D channels. The network node time division multiplexes thephysical channel between a first group of cellular channels and a firstgroup of D2D channels. The network node frequency division multiplexesthe physical channel between a second group of cellular channels and thefirst group of D2D channels.

According to a second aspect of embodiments herein, the object isachieved by a network node for multiplexing a physical channel betweenthe network node and devices. The network node and the devices arecomprised in a mixed wireless network. The mixed wireless networkfurther comprises a cellular network comprising one or more cellularchannels and a D2D network comprising one or more D2D channels. Thenetwork node comprises a processing circuit configured to: a. timedivision multiplex the physical channel between a first group ofcellular channels and a first group of D2D channels, and b. frequencydivision multiplex the physical channel between a second group ofcellular channels and the first group of D2D channels.

Since the physical channel is multiplexed, co-channel and inter-channelinterference between cellular and D2D channels is avoided or reduced.The performance is thereby improved.

An advantage of embodiments herein is to provide a simplified PHYchannel design to avoid or reduce the co-channel and inter-channelinterference between cellular and D2D channels.

A further advantage according to embodiments herein is a PHY channeldesign that avoids or reduces the co-channel and inter-channelinterference between cellular and D2D channels, and yet maximizes theusage of radio resources.

A further advantage according to embodiments herein is the backgroundcompatibility provided with the current 3GPP LTE specification forcellular systems in terms of HARQ timing.

A yet further advantage according to embodiments herein is a simple andflexible implementation for a network to control the ratio of cellularand D2D devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments herein are described in more detail withreference to attached drawings in which:

FIG. 1 is a schematic depiction of an effect of in-band emission.

FIG. 2 is a schematic block diagram illustrating embodiments in awireless communications system.

FIG. 3 is a flowchart depicting embodiments of a method in a networknode.

FIG. 4 is a schematic depiction of embodiments of frame structure ofcellular-only and D2D compatible UL subframes.

FIG. 5 is a graph the 3GPP requirement of in-band emission.

FIG. 6 is a schematic diagram illustrating embodiments of a PHY channeldesign.

FIG. 7 is a schematic diagram illustrating embodiments of a PHY channeldesign.

FIG. 8 is a schematic diagram illustrating embodiments of a PHY channeldesign.

FIG. 9 is a schematic diagram illustrating embodiments of a PHY channeldesign.

FIG. 10 is a schematic diagram illustrating embodiments of a PHY channeldesign.

FIG. 11 is a schematic diagram illustrating embodiments of a PHY channeldesign.

FIG. 12 is a schematic diagram illustrating embodiments of a PHY channeldesign.

FIG. 13 is a schematic diagram illustrating embodiments of a PHY channeldesign.

FIG. 14 is a schematic diagram illustrating embodiments of a PHY channeldesign.

FIG. 15 is a schematic diagram illustrating embodiments of a D2D HARQtiming.

FIG. 16 is a schematic block diagram illustrating embodiments of anetwork node.

DETAILED DESCRIPTION

FIG. 2 depicts a mixed wireless network 100 in which embodiments hereinmay be implemented. The mixed wireless network 100 is a wirelesscommunication network such as an LTE, Wideband Code Division MultipleAccess (WCDMA) Global System for Mobile Communications (GSM) network,any 3GPP cellular network, any 3GPP2 cellular network, a WorldwideInteroperability for Microwave Access (WiMAX) network, a WiFi network,or any wireless network or system.

Mixed wireless network 100 comprises a cellular network and a D2Dnetwork.

The mixed wireless network 100 comprises a network node 110. The networknode 110 may be a base station such as e.g. an eNB, eNodeB, or a HomeNode B, a Home eNode B, femto Base Station, BS, pico BS or any othernetwork unit capable to serve a device or a machine type communicationdevice in a mixed wireless network 100. In some particular embodiments,network node 110 may be a stationary relay node, a mobile relay node, ora device, such as a user equipment. The mixed wireless network 100covers a geographical area which is divided into cell areas, whereineach cell area is served by a network node, although, one network nodemay serve one or several cells. In the example depicted in FIG. 2,wherein the network node 110 is a base station, the network node 110serves a cell 115. The network node 110 may be of different classes suchas e.g. macro eNodeB, home eNodeB or pico base station, based ontransmission power and thereby also cell size. Typically, mixed wirelessnetwork 100 may comprise more cells similar to 115, served by theirrespective network nodes. This is not depicted in FIG. 2 for the sake ofsimplicity. The network node 110 may support one or severalcommunication technologies, and its name will depend on the technologyand terminology used. In 3GPP LTE network nodes, which may be referredto as eNodeBs or even eNBs, may be directly connected to one or morecore networks.

Mixed wireless network 100 also comprises at least a first device 121, asecond device 122, and a third device 123, which are located within thecell 115. Any of the first device 121, the second device 122, or thethird device 123 are wireless communication devices such as UE which arealso known as e.g. mobile terminals, wireless terminals and/or mobilestations. Devices are wireless, i.e., they are enabled to communicatewirelessly in a wireless network, sometimes also referred to as acellular radio system or cellular network. The communication may beperformed e.g., between two devices, between a device and a regulartelephone and/or between a device and a server. The communication may beperformed e.g., via a RAN and possibly one or more core networks,comprised within the wireless network.

The devices 121, 122 and 123 may further be referred to as mobiletelephones, cellular telephones, or laptops with wireless capability,just to mention some further examples. The devices 121, 122 and 123 inthe present context may be, for example, portable, pocket-storable,hand-held, computer-comprised, or vehicle-mounted mobile devices,enabled to communicate voice and/or data, via the RAN, with anotherentity, such as a server, a laptop, a Personal Digital Assistant (PDA),or a tablet computer, sometimes referred to as a surf plate withwireless capability, Machine-to-Machine (M2M) devices, devices equippedwith a wireless interface, such as a printer or a file storage device orany other radio network unit capable of communicating over a D2D linkand over a radio link in a cellular communications system. In someembodiments, the devices 121, 122 and 123 may further be referred to asnetwork nodes.

The first device 121 is comprised in the cellular network and in someembodiments wherein the first device 121 is not the network node 110, itis configured to communicate within the mixed wireless network 100 viathe network node 110 over a radio link 131, when the first device 121 ispresent in the cell 115 served by the network node 110.

In this example, the second device 122 and third device 123 are alsolocated within the cell 115. However, in other embodiments, either thesecond device 122 and/or the third device 123 may be located in anothercell which is in the neighbourhood of the cell 115, but within radiorange of each other. The second device 122 and third device 123 areconfigured to communicate within the mixed wireless network 100 via thenetwork node 110 or another network node serving the neighbouring cell,over radio links such as, e.g., a radio link 132, in some embodimentswherein the second device 122 is not the network node 110, and a radiolink 133, in some embodiments wherein the third device 123 is not thenetwork node 110, respectively, when the second device 122 and the thirddevice 123 are present in the cell 115 served by the network node 110 orin the adjacent cell served by the other network node. The second device122 and the third device 123 are also capable of communicating with eachother, or other devices using wireless D2D communication over, forexample, a D2D link 140, and are comprised in the D2D network.

Each of the devices 121, 122 and 123 may be configured to communicateusing one of the cellular or D2D communication, or with both. Howeverfor the purposes of explanation, in the following discussion, the firstwireless device 121 is understood to be using cellular communication andthe second wireless device 122 and the third wireless device 123 areunderstood to be using D2D communication.

As mentioned earlier, in the mixed cellular and D2D wireless network100, an inter-system interference problem arises from the co-existenceof the cellular and D2D systems in the same network. The D2Dcommunications may be located on cellular UL resources, which aretypically characterized with lighter traffic.

In some embodiments, the D2D feature may be considered to be implementedbased on a 3GPP Frequency-Division Duplexing (FDD) and a Time-DivisionDuplexing (TDD) LTE framework. As explained earlier, given the PHYchannel structure in the LTE system described in the background section,the co-existence of the cellular and D2D systems in the same mixedwireless network 100 may result in two types of interference: 1) co-RBinterference, i.e., interference on the same RB; and 2) inter-RBinterference due to in-band emission, i.e., the interference fromallocated RBs to unallocated RBs, within the band in the time dimension.

Thus, a way to overcome the interference problem existing in a mixedwireless network 100 is needed, so that cellular and D2D communicationsmay take place without too much interference. Embodiments herein aim toovercome this interference problem by designing the PHY channel for themixed network so that co- and/or inter-channel interference areminimized or avoided.

In principle, and in order to solve the co-RB interference, i.e.,interference on the same RB, problem, the network node 110 maypre-configure the devices to measure the interference and based on themeasurement report from the devices, and schedule the devicesaccordingly, to avoid collision of cellular transmission and D2Dreception. However, users may want to establish D2D communications atany time, while some of the cellular channels, such as the cellularChannel Quality Indicator (CQI), and Dedicated-Scheduling Request (D-SR)Physical Uplink Control Channel (PUCCH) channels, are prescheduled witha fixed timing and resource allocation, i.e., statically preconfigured.If the D2D communications are allowed to take place at any time, i.e. onany radio resources, they may collide with the transmissions that arestatically preconfigured by the network, and the cellular transmissions,which are typically transmitted at higher power, may interfere with theD2D communications, which are typically transmitted with lower power.Therefore, the network node 110 may need to take this into account inorder to avoid interference. The same scheduling may not be applied toall the channels. The scheduling may be tailored to the transmissioncharacteristics of every channel, such as resource allocation andtransmission power adjustment. For example, devices which are located inthe center of cell 115, may be transmitting with lower power, andtherefore causing less interference, than devices that are located inthe off-center portions of the cell 115, which may cause higherinterference. Transmission from devices that are located far-away fromother devices, may also be received by a device with lower power thantransmission from devices that are nearby, which may also cause higherinterference. The network node 110 may then take these differenttransmission/reception characteristics into account when scheduling thedifferent devices in the cell 115, as will be described later.

Embodiments of a method in the network node 110 for multiplexing aphysical channel between the network node 110 and the devices 121, 122,123 will now be described with reference to the flowchart depicted inFIG. 3. As mentioned above, the network node 110 and the devices 121,122, 123 are comprised in the mixed wireless network 100. The mixedwireless network 100 comprises the cellular network comprising one ormore cellular channels and the D2D network comprises one or more D2Dchannels. The network node 110 may be one of: a base station, astationary relay node, a mobile relay node, the first device 121, thesecond device 122, the third device 123 and a wireless device other thanthe first device 121. the second device 122 and the third device 123.

The method comprises the following actions, which actions may as well becarried out in another suitable order than that described below. In someembodiments, all the actions may be carried out, whereas in otherembodiments only some action/s may be carried out.

Action 301

To handle the interference problem of the mixed wireless network 100, inthis action, the network node 110 addresses the issue of the staticallypreconfigured channels. Due to fact that the interference caused bythese channels varies over time, in accordance with their scheduling,interference management of these channels may require repeatedreconfiguration and therefore high signaling overhead. In order to avoidthis repeated reconfiguration, and therefore in order to savereconfiguration signaling overhead, the network node 110 schedules someof the cellular channels and some of the D2D channels at differenttimes, so that they do not transmit at the same time and interfere witheach other. Thus, in this action, the network node 110 performs timedivision multiplexing in the physical channel between a first group ofcellular channels and a first group of D2D channels to avoiduncontrollable inter-channel interference. This is implemented jointlyby downlink control signalling from the network node 110, e.g., by DCI(Downlink Control Indicator), MAC CE (Medium Access Control layerControl Element) and RRC (Radio Resource Control) signalling. In someembodiments, the first group of cellular channels may comprise one ormore cellular channels that are prescheduied with a fixed timing andresource location. In some particular embodiments, the first group ofcellular channels may comprise the PUCCH D-8R/CQL channel, and the firstgroup of D2D channels may comprise a D2D Control Channel (DCCH) and aD2D Shared Channel (DSCH). In some particular embodiments, the firstgroup of cellular channels 411,412 may further comprise a PUCCHAcknowledgement/Negative Acknowledgement (A/N) channel.

The DCCH, may be used by the D2D pair in a similar way as the cellularPUCCH, which may be used to carry Hybrid Automatic RetransmissionRequest (HARQ) Acknowledgement/Negative Acknowledgement (A/N) feedback,and the existing format of PUCCH design may be reused by the DCCH. TheDSCH, is used by D2D in a similar way like cellular Physical UplinkShared Channel (PUSCH) which may be used to carry D2D data transmission,in-band control signaling of HARQ A/N, CQI, Buffer Status Report (BSR)Power Head Room (PHR) and etc. . .

The time division multiplexing between the first group of cellularchannels and the first group of D2D channels to avoid inter-channelinterference, may result in two types of UL subframe, i.e., acellular-only subframe and a D2D and cellular-compatible subframe. Thisis depicted in a particular embodiment in FIG. 4, which shows a physicalchannel 400, a cellular-only subframe 401 and a D2D andcellular-compatible subframe 402, the first group of cellular channels411, 412, a second group of cellular channels 421 and the first group ofD2D channels 431, 432. The physical channel 400 is time divisionmultiplexed between the first group of cellular channels 411, 412, whichare associated with the cellular-only subframe 401, and the first groupof D2D channels 431, 432, which are associated with the D2D andcellular-compatible subframe 402. As depicted, in the embodiment of FIG.4, the first group of cellular channels 411, 412 comprises a cellularPUCCH D-SR/CQI, PUCCH A/N and a PUSCH, the second group of cellularchannels 421 comprises a PUCCH A/N, and the first group of D2D channels431, 432 comprises a DCCH and a DSCH. FIG. 4 will be described furtherdown below.

The time division multiplexing between the first group of cellularchannels and the first group of D2D channels provides a method toovercome the problem of in-band emission from statically preconfiguredcellular transmission to D2D communications.

Action 302

For other channels that are not statically preconfigured, such as forexample the cellular PUCCH A/N, the network node 110 may rely on thedynamic scheduling of channels in the mixed wireless network 100, suchas the DL Physical Downlink Shared Channel (PDSCH) to coordinate theinterference. This is because there is a fixed timing and resourcelocation mapping relationship between PDSCH and uplink transmission ofPUCCH for ACK/NACK feedback, i.e., 4 ms after the PDSCH on a specificresource location calculated based on the scheduling of PDSCH.Therefore, a way to avoid the interference from PUCCH, i.e., theACK/NACK feedback, may be to restrict the downlink data transmission onPDSCH. Compared with CQI D-SR, it is actually not possible to achievetime division multiplexing with PUCCH A/N, since a HARQ A/N is triggeredby the PDSCH in every DL subframe. For these channels, the network node110 schedules some of the cellular channels and some of the D2D channelsin different ranges of frequencies, so that they do not interfere bytransmitting in each other's frequencies.

Thus, in this action, the network node 110 also performs frequencydivision multiplexing in the physical channel 400 between a second groupof cellular channels 421 and the first group of D2D channels 431, 432,by controlling the resource allocation of both cellular uplink and D2Ddata transmission. In some embodiments, the second group of cellularchannels 421 may comprise one or more cellular channels, such as a PUCCHA/N, channel, that are dependent on the signalling of another cellularchannel. The first group of D2D channels 431, 432 is the same as thatdescribed above.

A mentioned earlier, in some embodiments, the time division multiplexingand frequency division multiplexing actions discussed above may resultin a physical channel which may comprise two types of subframes: acellular-only subframe 401 and a D2D and cellular-compatible subframe402. The cellular-only subframe 401 is associated with the first groupof cellular channels 411, 412, and the D2D and cellular-compatiblesubframe 402 is associated with the second group of cellular channels421 and the first group of D2D channels 431, 432. In some embodiments,such as that depicted in FIG. 4, the cellular-only subframe 401 is thetraditional cellular UL subframe, which may comprise cellular PUCCH andPUSCH, which are frequency division multiplexed, and the D2D andcellular-compatible subframe 402 may comprise cellular PUCCH A/N, andD2D DCCH and DSCH.

By allocating cellular devices, such as the first device 121, in the D2Dand cellular-compatible subframes 402, the aim is to achieve highspectrum efficiency from reuse. This scheme may provide the possibilityof resource reusing on D2D and cellular-compatible subframes 402. Ifthis is not performed, D2D communications may use the resources in adedicated way to avoid inter-system interference. However, in theseembodiments, the reuse gain will be lower. In some particularembodiments, at least one of the first group of cellular channels 411,412 and the second group of cellular channels 421 may further comprise acellular PUSCH. However, in other embodiments, there may not be acellular PUSCH in the D2D and cellular-compatible subframe 402. In theselater embodiments, there may not be cellular devices reusing theresources with D2D communications.

Action 303

In some embodiments, for each cellular device 121 to be allocated oralready allocated into the D2D and cellular-compatible subframe 402, thenetwork node 110 may obtain information about interference of one ormore active D2D devices 122, 123 in the D2D and cellular-compatiblesubframe 402 into which each cellular device 121 is to be allocated oris already allocated. This may be done, for example, by pre-configuringthe D2D devices measurement on a set of cellular reference signals (RS).When any cellular RS may be identified as a high interference source, itmay be reported to the network.

As mentioned earlier, the interference provoked by a channel may dependon the channel's transmission power. The transmission power varies fromdevice to device, depending on their location within the cell 115. Forexample, devices which are located in the cell-center of cell 115, maybe transmitting with lower power, and therefore, causing lessinterference, than devices that are located in the off-center portionsof the cell 115, which may cause higher interference. Devices that arelocated far-away from other devices, may also be received with lowerpower, and therefore cause less interference, than devices that arenearby, which may cause higher interference. The network node 110 maythen take these different transmission/reception characteristics intoaccount when scheduling the different devices of the cell 115 in the D2Dand cellular-compatible subframe 402. Therefore, to solve the in-bandemission problem, the network node 110 may need to avoid scheduling D2Dand nearby cellular devices in the neighboring RB in the same slot, notonly the same RB. That is, the network node 110 may schedule onlycell-center, i.e., low transmission power, cellular devices, in the sameslot. For higher cellular transmission power, maximum 23 dBm forcellular devices, the interference level may be higher even for far-awayneighboring RBs, e.g., around −80 dBm as shown in FIG. 5. Therefore, inother embodiments, the network node 110 may rely on the dynamic DLscheduling, in order to avoid a high-power channel in the D2D andcellular-compatible subframe. For example, it may not desirable that adevice sends an A/N feedback in the 5-th UL subframe. The network node110 has no UL scheduling control, since the A/N timing and location isone-to-one mapped to the DL data. However, the network node 110 maycontrol the DL scheduling, and force the DL scheduling so that thedevice is not scheduled in the 1st DL subframe, so that no device isscheduled in 5th UL subframe. The network node 110 may determine whichinterference level is acceptable for D2D communications. This level willset the threshold above which interference may be too high for D2Dcommunication and therefore, the network node 110 may need to schedulethe devices accordingly in the D2D and cellular-compatible subframe.This threshold may be determined, for example, by A, the target SINR,signal to interference and noise ratio, of D2D communication, and B, theachieved D2D signal power, also taking into account of C, theinter-frequency loss ratio of interference jointly, as B*C/A.

In some embodiments, for each cellular device, such as the firstcellular device 121, to be allocated into the D2D andcellular-compatible subframe 402, all active D2D devices 122, 123 mayhave to detect the interference in advance to avoid co- or inter-channelinterference, and then send this information to the network node 110. Inother embodiments, it may be the network node 110 itself that measuresthe inter-channel interference from D2D devices 122, 123. This may bedone by interference measurement by all active D2D devices 122, 123 inthe D2D and cellular-compatible subframe 402, then the D2D device whodetects unacceptable co-or inter-channel interference, i.e.,interference above the interference threshold, may report to the networknode 110. This interference safety level or threshold may be differentfor co- and inter-channel interference, considering the in-bandemission, so that the interference report may indicate that theco-channel interference is harmful, but the inter-channel interferenceis acceptable.

Thus, in some embodiments, obtaining information about interferencecomprises one of: measuring the interference, and receiving theinformation about interference from at least one of the D2D devices 122,123. This may be implemented by pre-configuring a Radio ResourceManagement (RRM) measurement and report mechanism of the devices 122,123 via RRC signalling, then as long as the trigger condition may besatisfied, i.e., some threshold value may be achieved, a large path-lossbetween a network node and the device, when the signal of theneighboring cell is above a specific level, etc., the device 122, 123may send a measurement report to the network node 110.

In some embodiments, the cellular and D2D devices causing interferencedue to location or power of transmission, may be known by the network byanalyzing when a PHR report from one of the cellular devices indicatesthat a room for device power boosting is above a certain threshold. ThePHR is an index reported by a device to indicate an estimated powerheadroom, i.e., a difference between a nominal device maximum transmitpower and the estimated power for PUSCH transmission in the currentsubframe, expressed in dB.

In other embodiments, the potential interference of the devices may bedetermined by location or positioning methods. Thus, in someembodiments, the devices transmitting below a first power threshold,such as cell-center devices and devices far-away from D2D devices 122,123, may be detected by reporting their locations to the network node110 by a positioning sensor such as a Global Positioning System (GPS).

In some embodiments, this/these measurement/s may be carried out by D2Ddevices, such as 122 and 123. Relying on GPS and the PHR involves lowersignalling overhead in comparison with measurement reports. Therefore,in some embodiments where the network node 110 may just want to identifythe cell-center devices, i.e., a subset of the low-interference devices,it may just rely on GPS and/or PHR.

Action 304

The scheduling of cellular and D2D channels in the D2D andcellular-compatible subframe 402 may result in an inter-RB, i.e.,in-band, interference problem, as explained above in the backgroundsection, due to the high-power of transmission of the cellular channelsallocated near the frequency of transmission of the low-power oftransmission D2D channels. Some frequency separation, i.e., margin, maybe allowed to overcome this problem between the allocation of thehigh-power of transmission cellular channels and the low-power oftransmission D2D channels in the D2D and cellular-compatible subframe402. That is, to not allocate a certain frequency range to any channels.

Therefore, in some embodiments, the network node 110 may set a frequencymargin 440, such as an RB margin, between the second group of cellularchannels 421 and the first group of D2D channels 431, 432 to avoidin-band interference. This may be achieved by controlling the resourceallocation of both cellular uplink and D2D data transmission. So thenetwork node 110 may schedule the second group of cellular channels 421and the first group of D2D channels 431, 432 in two allocations, with asufficiently large margin in-between the two to avoid, or reduce,inter-frequency interference. The larger the margin in-between is, theless inter-frequency interference the second group of cellular channels421 and the first group of D2D channels 431, 432 may cause to eachother.

In some embodiments, an RB margin may be used to avoid the interferencefrom channels in the second group of cellular channels 421, such as thePUCCH A/N.

In some embodiments, for the example as that shown in FIG. 4, the D2DDCCH may be allocated in the band center, to provide the largest RBmargin 440 from the cellular PUCCH, which is located on the outersegments of the subframe.

The question then arises as to how large may the RB margin 440 be inorder to avoid interference between the channels allocated in the D2Dand cellular-compatible subframe 402. As shown in FIG. 5, according tothe 3GPP requirement, for a 20 MHz LTE system, a 0 dBm cellular ULBinary Phase-Shift Keying/Quadrature Phase-Shift Keying, BPSK/QPSK,transmission may restrict the in-band interference to different levelsto neighboring RBs, but maintain a stable level from the 7-th RB. Thus,an RB margin of 7 RBs may ensure that the in-band emission stays at −105dBm, which is acceptable for D2D communication.

Thus, in some embodiments, the RB margin 440 set between the channels ofthe D2D and cellular-compatible subframe 402 may comprise 7 or more RBs.In some particular embodiments, the RB margin 440 may be 7 RBs.

In some embodiments, the setting of the RB margin 440 may be dynamic,based on interference avoidance. That is, it may or it may not be used,based on whether the obtained interference is above or below theinterference threshold described earlier. In other words, if theinter-RB interference is measured as acceptable even for the nearest RB,e.g., −105 dBm, then there may be no need for such RB margin 440. Forexample, in some embodiments, the location of the cellular PUSCH and theD2D DSCH may be decided dynamically by the network node 110 consideringinterference avoidance, i.e., they may not be necessarily separated bythe RB margin 440. Thus, in some embodiments, the setting of thefrequency margin 440 may be performed when the obtained informationabout interference is above the interference threshold.

Action 305

As explained earlier, in some embodiments, co-channel and inter-channelinterference measurement may be required in order to carry outscheduling and resource reuse in the D2D and cellular-compatiblesubframe 402.

In the embodiments where interference information is obtained by thenetwork node 110, co-scheduling, namely, pairing of safe cellulardevices such as the first device 121 and the D2D devices 122, 123 maycontinue until an interference report from either D2D devices 122, 123or the network node 110 itself points out that the interference becomesunacceptable, i.e., above the interference threshold, for example, dueto device mobility. Then, the interfering cellular device or theinterfered D2D device may be dropped out of the co-scheduling group, andbe scheduled in the cellular-only subframe 401 or the D2D andcellular-compatible subframe 402.

Thus, one way of overcoming the in-band interference problem is torestrict the allocation of cellular devices, such as the first device121, in the D2D and cellular-compatible subframe 402 based ontransmission power. For example, only cell-center devices, i.e., lowtransmitting power devices, may be allowed in their respective positionin the D2D and cellular-compatible subframe 402. In these embodiments,there may be a RB margin 440, such as that described earlier, between,for example, the cellular PUCCH and the D2D DSCH and/or DCCH. Anotheroption is that the cellular devices which are far from the D2D devices,i.e., may be also cell-edge, and may be implemented by GPS assistance,or pathloss/interference measurement by, for example, D2D devices, maybe scheduled in the corresponding DL subframe. In these embodiments,there may be a smaller or no RB margin 440.

The first option may be easier to implement than the second, since thelatter relies on D2D devices measurement which may cause more signallingoverhead, but it may result in a restriction of the D2D RB usage to someextent, due to the usage of the RB margin 440, for the purposes oftransmission. Both options may depend on the scheduling implementationand may be time-varying. In some embodiments in which the cellular PUSCHis detected as causing acceptable interference by D2D measurement, itmay be located at the RB margin 440 space, so that still all the RBs maybe used.

In this action and in base of the foregoing, in some embodiments whereinthe D2D and cellular-compatible subframe 402 has a position for thesecond group of cellular channels 421, the network node 110 may scheduleonly cellular devices 121 that are transmitting below a first powerthreshold in the position for the second group of cellular channels 421.The first power threshold is that, underneath which the interferencecaused is acceptable by D2D measurement, i.e., below the interferencethreshold described above.

In other embodiments, the network node 110 may rely on dynamic DLscheduling to avoid the corresponding high-power A/N in the D2D andcellular-compatible subframe, since the timing relationship between DLPDSCH and UL HARQ A/N is fixed in the current 3GPP LTE system, so thenetwork node 110 may need to work around this fixed relationship andschedule the remaining channels according to the potentialinterferences.

In some particular embodiments, in order to avoid harmful interferencefrom PUCCH A/N to the frequency division multiplexed D2D DCCH/DSCH inthe D2D and cellular-compatible subframe 402, only cell-center cellulardevices, i.e., low transmission power cellular devices, may be scheduledin the corresponding DL PDSCH position.

Thus, in some embodiments, the network node 110 may decide a location inthe physical channel of the cellular and the D2D channels dynamically,based on interference avoidance. That is, the network node 110 maydecide a frequency and/or time interval, i.e., a position. In the D2Dand cellular-compatible subframe 402 of the cellular and the D2Dchannels dynamically, based on the obtained information aboutinterference, so that the obtained information about interference iswithin a determined interference threshold, such as the interferencethreshold described earlier. For example, if the interference from PUCCHat band-edge is high, then the network node 110 may need to allocate D2Dchannels at band-center with some frequency margin in-between toalleviate the interference. Otherwise no resource margin may be need.Another example may be, for cellular data transmission of PUSCH, ifthere are already multiple D2D devices using different resources, thenetwork node 110 may let the cellular PUSCH reuse the resources with D2Ddevices, but it should select the D2D device for which no harmfulinterference would be caused by this cellular device. In some particularembodiments, the cellular channel whose frequency and/or time intervalin the D2D and cellular-compatible subframe 402 may be decideddynamically may be the PUSCH channel and the D2D channel may be the DSCHchannel. The dynamic decision is carried out to avoid interference, andthe trigger is the interference relationship, which information isobtained by the network, relying, in some embodiments, on a measurementreport from D2D devices 122, 123.

In the embodiments in which the DCCH is located at band-center, it maycause the problem to the localized scheduling of cellular ULtransmission, which originally may be designed for continuous RBallocation. However, considering embodiments using the release-10 LTE,where multi-cluster PUSCH transmission for cellular devices 121 isallowed, i.e., the cellular UL transmission does not need to be oncontinuous RBs, the D2D DCCH in the band center may cause little problemfor the scheduling.

Without inter-system interference information, the most robust way toovercome the interference problem may be to locate cellular transmissionin the cellular-only subframe 401, and locate D2D transmission in theD2D and cellular-compatible subframe 402 without cellular PUSCH, butwith RB margin 440 from PUCCH.

As explained in the preceding action, in some embodiments, in order toavoid harmful interference from some high power of transmissionchannels, such as the PUCCH A/N, to lower power of transmission channelssuch as the frequency division multiplexed D2D DCCH/DSCH in the D2D andcellular-compatible subframe, only cell-center cellular devices may bescheduled in the corresponding DL PDSCH position. In some embodiments,no scheduling restriction may be needed in the corresponding DL PDSCHposition in the cellular-only UL subframe, since no D2D channels may beallocated there and there may be no need to consider the inter-systeminterference to avoid.

Therefore, in some embodiments, scheduling by the network node 110 forcellular devices 121 in the cellular-only subframe 401 may beunrestricted.

The foregoing discussion has focused on the description of the ULsubframes, where the D2D channels may typically be allocated. Similarscheduling actions may be taken by the network node 110 on DL subframes,which will not be repeated here for the sake of simplicity.

As a result of actions 301-305 just described, and in order to avoidinterference from high power transmissions, such as from the PUCCH A/Ncellular channel to the lower power of transmission D2D communications,in mixed wireless network 100, a subframe mapping relationship of DL andUL subframe types, such as that depicted in the embodiment of FIG. 6,may take place. This mapping may be between the data transmission onPDSCH and the ACK/NACK feedback on PUCCH, which is a fixedtiming/location mapping by the 3GPP specifications. In FIG. 6,cellular-only DL/UL subframes 401 are depicted in black, where nocellular device restriction is required. D2D and cellular-compatibleDL/UL subframes 402 are depicted in white, where onlycell-center/far-away cellular devices may be scheduled in DL subframe.Cellular devices causing no/acceptable co-/inter-channel interferencemay be scheduled in UL subframe in a FDD LTE system. In an FDD system,the transmitter and receiver operate at different carrier frequencies.Patterned subframes may be cellular-only 401 or D2D andcellular-compatible subframes 402, depending on traffic, as explainedlater, in actions 306 and 307. For the TDD system, since the DL and ULresources are on the same carrier frequency, the subframe pattern designhas to take into account the TDD configuration of the system as well.

In some embodiments, the co-/inter-RB interference measurement describedin Action 303 may continue during the data transmission procedure, wherethe information of cellular device reference signal (RS) configurationmay be necessary. This information may be sent by the network node 110to the D2D devices 122,123, in order to measure the specific RSs, sothat the harmful interfering cellular devices may be identified, whichmay be later reported by the D2D devices to the network node 110. Insome embodiments, this interference measurement/report may not be at theco-RB cellular device, but at inter-RB cellular device, so this maycause a signaling overhead considering the full dynamic scheduling ofcellular devices. While co-RB interference concerns the cellular devices121 reusing the same resources, for inter-RB interference, all thecellular devices 121 on the same time slot may have to be monitored,which represents an increment in signaling overhead. Therefore, in someembodiments, in order to reduce signaling overhead, a semi-persistentscheduling of cellular devices 121 on the D2D and cellular-compatiblesubframes 402 may be employed, i.e., the cellular RS information may notchange a lot during the data transmission procedure. The semi-persistentscheduling may be defined as a semi-static scheduling scheme, i.e., theresource scheduling may repeat periodically on the same resource set.

Action 306

In this action, the network node 110 may position repetitivelycellular-only 401 and D2D and cellular-compatible subframes 402 withinthe physical channel 400, with specific resource periodicity. Forexample, it could repeat every 8 ms, in order to co-exist with thetraditional FDD cellular HARQ process. All of these depend on thecorresponding scheduler implementation, i.e., on the time when a device121, 122, 123 may receive a resource grant.

In some embodiments, the network node 110 may position repetitively thecellular-only 401 and D2D and cellular-compatible subframes 402 withinthe physical channel 400 with a timing pattern, which is based on a HARQtiming of the cellular network.

One factor to take into account when designing a PHY channel 400 in amixed wireless network 100 is the timing of the cellular system HARQ forboth FDD and Time-division duplexing (TDD) systems. HARQ is thesimultaneous combination of Automatic Retransmission request (ARQ), andForward Error Correction (FEC). It enables the overhead of errorcorrection to be adapted dynamically depending on the channel quality.When HARQ is used, if the errors may be corrected by FEC, then noretransmission is requested; if the errors may be detected but notcorrected, a retransmission is requested. TDD is the application oftime-division multiplexing to separate outward and return signals.Compared with the FDD system, where the HARQ timing is more simplified,the HARQ timing for the TDD system is TDD configuration specific andthus more complicated.

According to the current 3GPP FDD LTE specification, the UL HARQ isimplemented in a synchronous way, i.e., a new UL transmission in then-th Transmission Time Interval (TTI) may be ACK/NACKed by the DL in then+4 subframe, and it may cause a re-transmission in the n+8 subframe, inthe FDD system. Thus, if the allocation of cellular-only and D2D andcellular-compatible subframes 401, 402 may be designed for backwardscompatibility with the timing of the cellular system HARQ for both FDDand the TDD systems, the cellular-only subframe may be repeated at leastevery 8 subframes. Given this pattern of repetition of every n+8subframe dictated by the current 3GPP FDD LTE specification, the networknode 110 may dynamically schedule the remaining 7 subframes in-betweenthe first and n+8 subframes. Thus, a repeating pattern for cellular-onlysubframes of every 8, 4, or 2 subframes may be appropriate, asillustrated in FIGS. 6-8, where the arrows denote the relationshipbetween the Physical HARQ Indicator channel (PHICH)-PUSCH andPUSCH-PHICH timing relationship, and it is similar for FIGS. 6-14. TheD2D system HARQ timing may then adapt to the different repetitionfactor.

The repetition factor of every 4 subframes, as shown in the embodimentof FIG. 6, may be associated with a number of advantages and a number ofdisadvantages.

Among the advantages of a repetition factor of 4 are that the D2D mayimplement a similar HARQ timing as shown in FIG. 15, i.e., the newtransmission in the n-th TTI is feedback by A/N in the n+4 subframe onDCCH, following by a possible re-transmission in the n+8 subframe. Inother words, each n-th D2D and cellular-compatible subframe includes A/Nfor the n+4 subframe, new transmission in the n-th subframe andre-transmission for the n+8 subframe.

Among the disadvantages of a repetition factor of 4 are that for thecellular system, the PUCCH periodicity may be only configured as 4×subframes, e.g., 20 ms, which may be however acceptable for D-SRaccording to an on-going study of 3GPP Rel-11 eDDA WI. Compared with therepetition factor of 8, where the D-SR periodicity may only be 40 ms atleast, the periodicity of a smaller D-SR may be beneficial for thenetwork to be kept updated on the DL channel quality in a timely way.

In the embodiments in which the repetition factor may be every 8subframes, as shown in FIG. 7, the D2D may have to implement an extendedHARQ timing, i.e., the n-th subframe may only be mapped to A/N in then+8 subframe, and a re-transmission may be further extended to the n+16subframe. In other words, the number of HARQ processes may be extended.These embodiments may be associated with a number of advantages and anumber of disadvantages.

Among the advantages of a repetition factor of 8 are that this optionprovides more flexibility of cellular/D2D ratio control. That is, thenetwork node 110 may have 7 frames to dynamically allocate forcellular-only or D2D and cellular-compatible subframes, as opposed tothe 3 frames that may be available with a repetition factor of 4.

As stated above, among the disadvantages of a repetition factor of 8 arethat a larger PUCCH periodicity of 8× subframes may have to be used,e.g., 40 ms, which may be however acceptable for D-SR according toon-going study of 3GPP Rel-11 eDDA WI.

In the embodiments in which the repetition factor may be every 2subframes, as shown in FIG. 8, the conventional HARQ timing may beimplemented by D2D in a similar way. These embodiments may be associatedwith a number of advantages and a number of disadvantages.

Among the advantages of a repetition factor of 2 are that it may providemore options when set PUCCH D-SR periodicity, i.e., in the number of 2n,n is an integer. Almost all existing D-SR periodicity options in theexisting LTE network may be applied here, compared with the repetitionfactor of 4 or 8, where the periodicity may be restricted in someextent.

Among the disadvantages of a repetition factor of 2 are that the ratioof cellular-only and D2D and cellular-compatible subframes 401, 402 maybe fixed as 1:1. That is, the network node 110 may not have any framesto dynamically allocate for cellular-only or D2D and cellular-compatiblesubframes 401, 402, as opposed to the 3 frames that may be availablewith a repetition factor of 4 and the 7 frames that may be availablewith a repetition factor of 8.

A similar design may be extended to TDD system, as is shown in FIG. 9for a TDD configuration 0, in FIG. 10 for a TDD configuration 1, in FIG.11 for a TDD configuration 2, in FIG. 12 for a TDD configuration 3, inFIG. 13 for a TDD configuration 4, in FIG. 14 for a TDD configuration 6,respectively. The different configurations are for different forwardingand reverse link resource ratio, considering the D2D communication maybe a bi-directional transmission, the resource ratio may be adjustedaccording to the traffic type and channel quality jointly.

Similarly, for different TDD configurations, the resulting ratio controlflexibility and HARQ timing capability may be various. Please note thatfor subframe 3 and subframe 8 in TDD configuration 0, since there may beno DL PDSCH associated with the PUCCH A/N field, mainly due to less DLsubframes in this configuration, it may be more beneficial to locate theD2D DCCH at band-edge, without considering the interference from PUCCH.And for TDD configuration 5, since only 1 HARQ process may be allowed inUL, it may be hard to ensure backwards compatibility and of less need tofurther divide the single HARQ process between cellular and D2Dsub-systems, so no D2D and cellular-compatible subframe 402 may co-existin the configuration.

In some embodiments, in order to maintain compatibility of the cellulardevices 121 with the legacy HARQ timing, the network node 110 mayfurther allocate jointly subframes of a same HARQ process to only oneof: cellular-only 401 and D2D and cellular-compatible subframes 402, sothat all subframes corresponding to the same HARQ process are eithercellular-only 401 or D2D and cellular-compatible subframes 402, but notin a mixed way.

Action 307

Since the amount of cellular and D2D data traffic may vary in the mixedwireless network 100, network node 110 may need to allocate more or lesscellular-only and D2D and cellular-compatible subframes 401, 402,depending on the amount of traffic in each. In relation to FIGS. 6-15,this means that depending on how much cellular and D2D transmissionthere may be, the network node 110 may allocate the patterned subframesin the figures, to either cell-only subframes 401, or D2D andcellular-compatible subframes 402.

Thus, in this action, the network node 110 may adapt in the timedivision multiplexing 301 and the frequency division multiplexing 302, aratio of cellular-only 401 and D2D and cellular-compatible subframes402, dynamically, based on an amount of resources required by cellularsignalling and an amount of resources required by D2D signalling. Insome embodiments, this dynamic adaptation may be carried out accordingto traffic type and/or channel quality. In some embodiments, the trafficvolume may provide information of how many bits need to be sent, whilein some embodiments the channel quality may provide information of howmany resources needed per bit. By combining the two, the network node110 may know how many resources are needed for both cellular and D2Dcommunication, and therefore may be able to decide how to divide theresources between the two. Traffic type may be determined by inspectingthe data packet by using the existing technology of DPI (Deep PacketInspection) at the network node 110 side, or assisted by core networkentities like PDN Gateway. Channel quality may be acquired from aChannel State Information (CSI) report from the devices 121, 122 123.

To perform the method actions in the network node 110 described above inrelation to FIGS. 3-4 and 6-15 for multiplexing a physical channel 400,the network node 110 comprises the following arrangement depicted inFIG. 16. As mentioned above, the network node 110 and devices 121, 122,123 are comprised in a mixed wireless network 100, wherein the mixedwireless network 100 further comprises a cellular network comprising oneor more cellular channels and a D2D network comprising one or more D2Dchannels.

The network node 110 comprises a multiplexing circuit 1601, wherein themultiplexing circuit 1601 is configured to time division multiplex thephysical channel 400 between a first group of cellular channels 411, 412and a first group of D2D channels 431, 432, and frequency divisionmultiplex the physical channel 400 between a second group of cellularchannels 421 and the first group of D2D channels 431, 432.

In some embodiments, the physical channel 400 may comprise two types ofsubframes: a cellular-only subframe 401 and a D2D andcellular-compatible subframe 402, wherein the cellular-only subframe 401is associated with the first group of cellular channels, and the D2D andcellular-compatible subframe 402 is associated with the second group ofcellular channels 421 and the first group of D2D channels 431, 432.

In some embodiments, the first group of cellular channels 411, 412 maycomprise a cellular channel that is prescheduled with a fixed timing andresource location, and the second group of cellular channels 421 maycomprise a cellular channel that is dependent on the signalling ofanother cellular channel.

In some embodiments, the first group of cellular channels 411, 412 maycomprise a cellular PUCCH D-SR/CQI channel, the second group of cellularchannels 421 may comprise a PUCCH A/N channel and the first group of D2Dchannels 431, 432 may comprise a DCCH and a D2D DSCH.

In some embodiments, at least one of the first group of cellularchannels 411, 412 and the second group of cellular channels 421 mayfurther comprise a cellular Physical Uplink Shared Channel, PUSCH.

In some other embodiments, the first group of cellular channels 411, 412may further comprise a PUCCH A/N channel.

In some embodiments, the network node 110 may further comprise a settingcircuit 1602, which may be configured to set a frequency margin 440between the second group of cellular channels 421 and the first group ofD2D channels 431, 432.

In some of these embodiments, the frequency margin 440 may comprise 7 ormore physical resource blocks.

In some embodiments, wherein the devices 121, 122, 123 may comprisecellular devices 121 and D2D devices 122, 123, the network node 110 mayfurther comprise an obtaining circuit 1603 which is configured to, foreach cellular device 121 to be allocated or already allocated into theD2D and cellular-compatible subframe 402, obtain information aboutinterference of one or more active D2D devices 122, 123 in the D2D andcellular-compatible subframe 402 into which each cellular device 121 isto be allocated or is already allocated.

In some of these embodiments, obtain information about interference maycomprise one of: to measure the interference, and to receive theinformation about interference from at least one of the D2D devices 122,123.

In some embodiments, the setting circuit 1602 may be further configuredto set the frequency margin 440 when the obtained information aboutinterference is above an interference threshold.

In some embodiments, the D2D and cellular-compatible subframe 402 mayhave a position for the second group of cellular channels 421, and thenetwork node 110 may further comprise a scheduling circuit 1604configured to schedule only cellular devices 121 that are transmittingbelow a first power threshold in the position for the second group ofcellular channels 421.

In some embodiments, the network node 110 may further comprise apositioning circuit 1605 further configured to position repetitivelycellular-only 401 and D2D and cellular-compatible subframes 402 withinthe physical channel 400.

In some of these embodiments, the positioning circuit 1605 may befurther configured to position repetitively cellular-only 401 and D2Dand cellular-compatible subframes 402 within the physical channel 400with a timing pattern, wherein the timing pattern is based on a HARQtiming of the cellular network.

In some embodiments, the network node 110 may further comprise anallocating circuit 1606 configured to allocate jointly subframes of asame HARQ process to only one of: cellular-only 401 and D2D andcellular-compatible subframes 402, so that all subframes correspondingto the same HARQ process are either cellular-only 401 or D2D andcellular-compatible subframes 402.

In some embodiments, the network node 110 may further comprise anadapting circuit 1607 configured to adapt, in time division multiplexingand frequency division multiplexing, a ratio of cellular-only 401 andD2D and cellular-compatible subframes 402, dynamically, based on anamount of resources required by cellular signalling and an amount ofresources required by D2D signalling.

In some embodiments, the network node 110 may further comprise adeciding circuit 1608 further configured to decide a frequency and/ortime interval in the D2D and cellular-compatible subframe 402 of thecellular and the D2D channels dynamically, based on the obtainedinformation about interference, so that the obtained information aboutinterference is within a determined interference threshold.

In some embodiments, the network node 110 may be one of: a base station,a stationary relay node, a mobile relay node, the first device 121, thesecond device 122, the third device 123 and a wireless device other thanthe first device 121, the second device 122 and the third device 123.

The scheduling circuit 1603 may be comprised in a scheduler. Thescheduler may manage the cellular communications of devices such as thefirst device 121, as well as the D2D communications of devices such asthe second device 122 and the third device 123. The scheduler determinesif, which and when devices have the possibility to communicate in adirect D2D communication. The scheduler may provision a discovery signalto be used between two devices to determine their proximity and/or D2Dlink estimation. It may also assign resources for the D2D discoverysignal and/or a D2D data channel and/or a D2D control channel. It mayrelay information between the at least two devices, and it may configureconnection parameters for the at least two devices of the D2D link, suchas power setting, e.g., actual, min, max, coding and modulation schemes,segmentation configuration, e.g., transport block sizes, parametersand/or security keys for encryption/integrity protection, protocolparameters, which Radio Access Technology, spectrum/carrier to use forD2D link. Typically, the scheduler may be co-located with the networknode 110. The network node co-located with the scheduler may be in someembodiments: a base station, a stationary relay node -not pictured-, amobile relay node—not pictured—, the first device 121, the second device122, the third device 123, or a wireless device other than the firstdevice 121, the second device 122 and the third device 123. Thescheduler may be capable of communicating with devices such as the firstdevice 121, the second device 122 and the third device 123 over arespective scheduler link. The scheduler may also communicate with otherdevices over other D2D controller links.

The embodiments herein for handling a D2D communication may beimplemented through one or more processors, such as a processing circuit1609 in the network node 110 depicted in FIG. 16, together with computerprogram code for performing the functions and actions of the embodimentsherein. The program code mentioned above may also be provided as acomputer program product, for instance in the form of a data carriercarrying computer program code for performing the embodiments hereinwhen being loaded into the in the network node 110. One such carrier maybe in the form of a CD ROM disc. It may be however feasible with otherdata carriers such as a memory stick. The computer program code mayfurthermore be provided as pure program code on a server and downloadedto the network node 110.

The network node 110 may further comprise a memory circuit 1610comprising one or more memory units. The memory circuit 1610 may bearranged to be used to store data such as, the information received ormeasured by the processing circuit 1609 in relation to obtaining thedevice location and/or interference, and applications to perform themethods herein when being executed in the network node 110. Memorycircuit 1610 may be in communication with the processing circuit 1609.Any of the other information processed by the processing circuit 1609may also be stored in the memory circuit 1610.

In some embodiments, information regarding the location of the devicesmay be received from another structure in the mixed wireless network 100through a receiving port 1611. In some embodiments, the receiving port1611 may be, for example, connected to a positioning sensor, e.g., GPS.In other embodiments, the receiving port 1611 may be a network basedpositioning service via a corresponding communication protocol. Sincethe receiving port 1611 may be in communication with the processingcircuit 1609, the receiving port 1611 may then send the device locationinformation to the processing circuit 1609. The receiving port 1611 maybe configured to receive other information. In some embodiments,information regarding the interference of the devices may be receivedfrom another structure in the mixed wireless network 100 through thereceiving port 1611. Since the receiving port 1611 may be incommunication with the processing circuit 1609, the receiving port 1611may then send the device interference information to the processingcircuit 1609.

The information received or measured by the processing circuit 1609 inrelation to the location of the devices and/or obtaining theinterference of the devices 122, 123, may be stored in the memorycircuit 1610 which, as stated earlier, may be in communication with theprocessing circuit 1609 and the receiving port 1611.

The processing circuit 1609 may be further configured to sendinformation, such as transmission grants, through a sending port 1612,which may be in communication with the processing circuit 1609, and thememory circuit 1610

Those skilled in the art will also appreciate that the multiplexingcircuit 1601, the setting circuit 1602, the obtaining circuit 1603, thescheduling circuit 1604, the positioning circuit 1605, the allocatingcircuit 1606, the adapting circuit 1607 and the deciding circuit 1608described above may refer to a combination of analog and digitalcircuits, and/or one or more processors configured with software and/orfirmware (e.g., stored in memory) that, when executed by the one or moreprocessors such as the processing circuit 1609, perform as describedabove. One or more of these processors, as well as the other digitalhardware, may be included in a single application-specific integratedcircuit (ASIC), or several processors and various digital hardware maybe distributed among several separate components, whether individuallypackaged or assembled into a system-on-a-chip (SoC).

When using the word “comprise” or “comprising” it shall be interpretedas non-limiting, i.e. meaning “consist at least of”.

The embodiments herein are not limited to the above described preferredembodiments. Various alternatives, modifications and equivalents may beused. Therefore, the above embodiments should not be taken as limitingthe scope of the invention, which is defined by the appending claims.

1. A method in a network node (110) for multiplexing a physical channel(400), between the network node (110) and devices (121, 122, 123)comprised in a mixed wireless network (100), wherein the mixed wirelessnetwork (100) further comprises a cellular network comprising one ormore cellular channels and a Device-to-Device, D2D, network comprisingone or more D2D channels, the method comprising: time divisionmultiplexing (301) the physical channel (400) between a first group ofcellular channels (411, 412) and a first group of D2D channels (431,432); and frequency division multiplexing (302) the physical channel(400) between a second group of cellular channels (421) and the firstgroup of D2D channels (431, 432).
 2. The method of claim 1, wherein thephysical channel (400) comprises two types of subframes: a cellular-onlysubframe (401) and a D2D and cellular-compatible subframe (402), andwherein the cellular-only subframe (401) is associated with the firstgroup of cellular channels (411, 412), and the D2D andcellular-compatible subframe (402) is associated with the second groupof cellular channels (421) and the first group of D2D channels(431,432).
 3. The method of any of claims 1-2, wherein the first groupof cellular channels (411, 412) comprises a cellular channel that isprescheduled with a fixed timing and resource location, and wherein thesecond group of cellular channels (421) comprises a cellular channelthat is dependent on the signalling of another cellular channel.
 4. Themethod of any of claims 1-3, wherein the first group of cellularchannels (411, 412) comprises a cellular Physical Uplink Control ChannelDedicated-Scheduling Request/Channel Quality indicators, PUCCH D-SR/CQI,channel, the second group of cellular channels (421) comprises a PUCCHAcknowledgement/Negative Acknowledgement, PUCCH A/N, channel, andwherein the first group of D2D channels (431 432) comprises a D2DControl Channel DCCH and a D2D Shared Channel, DSCH.
 5. The method ofany of claims 1-4, wherein at least one of the first group of cellularchannels (411, 412) and the second group of cellular channels (421)further comprises a cellular Physical Uplink Shared Channel, PUSCH. 6.The method of any of claims 1-5, wherein the first group of cellularchannels (411, 412) further comprises a PUCCH A/N channel.
 7. The methodof any of claims 1-6, further comprising setting (304) a frequencymargin (440) between the second group of cellular channels (421) and thefirst group of D2D channels (431, 432).
 8. The method of claim 7,wherein the frequency margin (440) comprises 7 or more physical resourceblocks.
 9. The method of any of claims 2-8, wherein the devices (121,122, 123) comprises cellular devices (121) and D2D devices (122, 123),the method further comprising, for each cellular device (121) to beallocated or already allocated into the D2D and cellular-compatiblesubframe (402), obtaining (303) information about interference of one ormore active D2D devices (122, 123) in the D2D and cellular-compatiblesubframe (402) into which each cellular device (121) is to be allocatedor is already allocated.
 10. The method according to claim 9, whereinobtaining (303) information about interference comprises one of:measuring the interference, and receiving the information aboutinterference from at least one of the D2D devices (122, 123).
 11. Themethod of any of claims 9-10, wherein the setting (304) the frequencymargin (440) is performed when the obtained information aboutinterference is above an interference threshold.
 12. The method of anyof claims 2-11, wherein the D2D and cellular-compatible subframe (402)has a position for the second group of cellular channels (421), themethod further comprising: scheduling (305) only cellular devices (121)that are transmitting below a first power threshold in the position forthe second group of cellular channels (421).
 13. The method of any ofclaims 2-12, further comprising positioning repetitively (306)cellular-only (401) and D2D and cellular-compatible subframes (402)within the physical channel (400).
 14. The method of claim 13, whereinthe positioning repetitively (306) of cellular-only (401) and D2D andcellular-compatible subframes (402) within the physical channel (400) isdone with a timing pattern, and wherein the timing pattern is based on aHybrid Automatic Repeat Request, HARQ, timing of the cellular network.15. The method of claim 14, further comprising allocating jointlysubframes of a same HARQ process to only one of: cellular-only (401) andD2D and cellular-compatible subframes (402), so that all subframescorresponding to the same HARQ process are either cellular-only (401) orD2D and cellular-compatible subframes (402).
 16. The method of any ofclaims 2-15, further comprising adapting (307), in the time divisionmultiplexing (301) and the frequency division multiplexing (302), aratio of cellular-only (401) and D2D and cellular-compatible subframes(402), dynamically, based on an amount of resources required by cellularsignalling and an amount of resources required by D2D signalling. 17.The method of any of claims 9-16, further comprising deciding afrequency and/or time interval in the D2D and cellular-compatiblesubframe (402) of the cellular and the D2D channels dynamically, basedon the obtained information about interference, so that the obtainedinformation about interference is within a determined interferencethreshold.
 18. The method of any of claims 1-17, wherein the networknode (110) is one of: a base station, a stationary relay node, a mobilerelay node, the first device (121), the second device (122), the thirddevice (123) and a wireless device other than the first device (121),the second device (122) and the third device (123).
 19. A network node(110) for multiplexing a physical channel (400), between the networknode (110) and devices (121, 122, 123) comprised in a mixed wirelessnetwork (100), wherein the mixed wireless network (100) furthercomprises a cellular network comprising one or more cellular channelsand a Device-to-Device, D2D, network comprising one or more D2Dchannels, the network node (110) comprising: a multiplexing circuit(1601) configured to: a. time division multiplex the physical channel(400) between a first group of cellular channels (411, 412) and a firstgroup of D2D channels (431, 432); and b. frequency division multiplexthe physical channel (400) between a second group of cellular channels(421) and the first group of D2D channels (431, 432).
 20. The networknode (110) of claim 19, wherein the physical channel (400) comprises twotypes of subframes: a cellular-only subframe (401) and a D2D andcellular-compatible subframe (402), and wherein the cellular-onlysubframe (401) is associated with the first group of cellular channels,and the D2D and cellular-compatible subframe (402) is associated withthe second group of cellular channels (421) and the first group of D2Dchannels (431, 432).
 21. The network node (110) of any of claims 19-20,wherein the first group of cellular channels (411, 412) comprises acellular channel that is prescheduled with a fixed timing and resourcelocation, and wherein the second group of cellular channels (421)comprises a cellular channel that is dependent on the signalling ofanother cellular channel.
 22. The network node (110) of any of claims19-21, wherein the first group of cellular channels (411, 412) comprisesa cellular Physical Uplink Control Channel Dedicated-SchedulingRequest/Channel Quality Indicators, PUCCH D-SR/CQI, channel, the secondgroup of cellular channels (421) comprises a PUCCHAcknowledgement/Negative Acknowledgement, PUCCH A/N, channel, andwherein the first group of D2D channels (431, 432) comprises a D2DControl Channel, DCCH and a D2D Shared Channel, DSCH.
 23. The networknode (110) of any of claims 19-22, wherein at least one of the firstgroup of cellular channels (411, 412) and the second group of cellularchannels (421) further comprises a cellular Physical Uplink SharedChannel, PUSCH.
 24. The network node (110) of any of claims 19-23,wherein the first group of cellular channels (411 412) further comprisesa PUCCH A/N channel.
 25. The network node (110) of any of claims 19-24,further comprising a setting circuit (1602) further configured to set afrequency margin (440) between the second group of cellular channels(421) and the first group of D2D channels (431 432).
 26. The networknode (110) of claim 25, wherein the frequency margin (440) comprises 7or more physical resource blocks.
 27. The network node (110) of any ofclaims 20-26, wherein the devices (121, 122, 123) comprises cellulardevices (121) and D2D devices (122, 123), and wherein the network node(110) further comprises an obtaining circuit (1603) configured to, foreach cellular device (121) to be allocated or already allocated into theD2D and cellular-compatible subframe (402), obtain information aboutinterference of one or more active D2D devices (122, 123) in the D2D andcellular-compatible subframe (402) into which each cellular device (121)is to be allocated or is already allocated.
 28. The network node (110)of claim 27, wherein to obtain information about interference comprisesone of: to measure the interference, and to receive the informationabout interference from at least one of the D2D devices (122, 123). 29.The network node (110) of any of claims 27-28, wherein the settingcircuit (1602) is further configured to set the frequency margin (440)when the obtained information about interference is above aninterference threshold.
 30. The network node (110) of any of claims20-29, wherein the D2D and cellular-compatible subframe (402) has aposition for the second group of cellular channels (421), and whereinthe network node (110) further comprises a scheduling circuit (1604)configured to: schedule only cellular devices (121) that aretransmitting below a first power threshold in the position for thesecond group of cellular channels (421).
 31. The network node (110) ofany of claims 20-30, further comprising a positioning circuit (1605)further configured to position repetitively cellular-only (401) and D2Dand cellular-compatible subframes (402) within the physical channel(400).
 32. The network node (110) according to claim 31, wherein thepositioning circuit (1605) is further configured to positionrepetitively cellular-only (401) and D2D and cellular-compatiblesubframes (402) within the physical channel (400) with a timing pattern,and wherein the timing pattern is based on a Hybrid Automatic RepeatRequest, HARQ, timing of the cellular network.
 33. The network node(110) of claim 32, further comprising an allocating circuit (1606)configured to allocate jointly subframes of a same HARQ process to onlyone of: cellular-only (401) and D2D and cellular-compatible subframes(402), so that all subframes corresponding to the same HARQ process areeither cellular-only (401) or D2D and cellular-compatible subframes(402).
 34. The network node (110) of any of claims 20-33, furthercomprising an adapting circuit (1607) configured to adapt, in timedivision multiplexing and frequency division multiplexing, a ratio ofcellular-only (401) and D2D and cellular-compatible subframes (402),dynamically, based on an amount of resources required by cellularsignalling and an amount of resources required by D2D signalling. 35.The network node (110) of any of claims 27-34, further comprising adeciding circuit (1608) further configured to decide a frequency and/ortime interval in the D2D and cellular-compatible subframe (402) of thecellular and the D2D channels dynamically, based on the obtainedinformation about interference, so that the obtained information aboutinterference is within a determined interference threshold.
 36. Thenetwork node (110) of any of claims 19-35, wherein the network node(110) is one of: a base station, a stationary relay node, a mobile relaynode, the first device (121), the second device (122), the third device(123) and a wireless device other than the first device (121), thesecond device (122) and the third device (123).